The nucleus is a membrane-bound organelle that controls all the cellular activities of the cell. It plays an important role in cell division. It is relatively large and spherical in shape and is composed of the following structures:
Nucleoplasm: It is the matrix of the nucleus that contains the nucleolus and chromatin. The nucleolus is made up of protein and RNA molecules and is the site for ribosome formation. It is a spherical structure that is not bound by any membrane. The chromatin reticulum found within the nucleoplasm is made up of DNA and histone proteins. It is highly entangled but at the time of cell division chromatin reticulum condenses into chromosomes.
Centrosome: The centrosome is made up of two cylindrical structures that lie perpendicular to each other called centrioles. These centrioles are linked with each other by interconnected fibers. Each centriole has a cartwheel-like arrangement which is made up of microtubule triplets that are evenly placed in a ring. A proteinaceous hub is present in the central part of a centriole which is connected to the triplets via radial spokes. The centrioles play a vital role in forming the spindle fibers and astral rays during cell division and also forms the basal body of cilia and flagella.
Answered by Pragya Singh | 11 months ago